Do you like to use diagrams illustrations and much more, but to face on camera? You should build a crystal clear whiteboard as Michael Peshkin.
His solution (an Open Source HW) was to develop a clear whiteboard that improves the experience of draftsman with a little trick in realtime with no post-production. Simply he flip the video in reproduction classroom time and the trick puts every writing hand on his face.
Moreover, to make a recording more clear, he use a 4x8 foot panel of architectural glass, lit internally from the upper and lower edges by bright white LEDs. This allow him to draw with fluorescent dry-erase markers on the glass, wherein the light travels to all parts by total internal reflection (TIR) and make glowing every sign for a more clear contrast.
The result it's very nice, you can watching it further down.